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Teach cvmach to emit the symbol table.

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This preserves the name and value of every symbol.  The type and other
info of a symbol might be lost.  In gdb, one can now "disas main" or
"disas '.ret'" to disassemble functions by name.

Most symbols are in sections, so I also teach cvmach to emit the Mach
section headers.  The entry point in plat/osx*/descr moves down to
make room for the section headers and LC_SYMTAB.

I fix some bugs in calculations of cvmach.  They were wrong if ROM had
a greater alignment than TEXT, or if DATA did not start on a page
boundary.  I introduce machseg[] to simplify the mess of variables in
main().  I declare most functions as static.  Also, cvmach becomes the
first program to #include <object.h>.
This commit is contained in:
George Koehler 2016-11-22 17:16:30 -05:00
parent 19310d2521
commit 98f2273d97
4 changed files with 332 additions and 92 deletions
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2
plat/osx/cvmach/build.lua
View file

@ -3,8 +3,6 @@ cprogram {
srcs = { "./cvmach.c" }, srcs = { "./cvmach.c" },
deps = { deps = {
"h+emheaders", "h+emheaders",
-- Next line only because object.h includes ansi.h
"modules+headers",
"modules/src/object+lib", "modules/src/object+lib",
} }
} }

418
plat/osx/cvmach/cvmach.c
View file

@ -4,12 +4,12 @@
*/ */
/* /*
* cvmach.c - convert ack.out to mach-o * cvmach.c - convert ack.out to Mach-o
* *
* Mostly pinched from aelflod (util/amisc/aelflod.c), which pinched * Mostly pinched from aelflod (util/amisc/aelflod.c), which pinched
* from the ARM cv (mach/arm/cv/cv.c), which pinched from the m68k2 cv * from the ARM cv (mach/arm/cv/cv.c), which pinched from the m68k2 cv
* (mach/m68k2/cv/cv.c). The code to read ack.out format using * (mach/m68k2/cv/cv.c). The code to read ack.out format using
* liboject is pinched from the Xenix i386 cv (mach/i386/cv/cv.c). * libobject is pinched from the Xenix i386 cv (mach/i386/cv/cv.c).
*/ */
#include <stdarg.h> #include <stdarg.h>
@ -19,11 +19,12 @@
#include <string.h> #include <string.h>
#include <out.h> #include <out.h>
/* Can't find #include <object.h>*/ #include <object.h>
/* Header and section table of ack.out */ /* Header and section table of ack.out */
struct outhead outhead; struct outhead outhead;
struct outsect outsect[S_MAX]; struct outsect outsect[S_MAX];
uint32_t ack_off_char; /* Offset of string table in ack.out */
int bigendian; /* Emit big-endian Mach-o? */ int bigendian; /* Emit big-endian Mach-o? */
int cpu_type; int cpu_type;
@ -48,6 +49,7 @@ enum {
#define MH_MAGIC 0xfeedface #define MH_MAGIC 0xfeedface
#define MH_EXECUTE 2 #define MH_EXECUTE 2
#define LC_SEGMENT 1 #define LC_SEGMENT 1
#define LC_SYMTAB 2
#define LC_UNIXTHREAD 5 #define LC_UNIXTHREAD 5
#define CPU_TYPE_X86 7 #define CPU_TYPE_X86 7
@ -68,7 +70,10 @@ enum {
/* sizes of Mach structs */ /* sizes of Mach structs */
#define SZ_MACH_HEADER 28 #define SZ_MACH_HEADER 28
#define SZ_SEGMENT_COMMAND 56 #define SZ_SEGMENT_COMMAND 56
#define SZ_SECTION_HEADER 68
#define SZ_SYMTAB_COMMAND 24
#define SZ_THREAD_COMMAND_BF_STATE 16 #define SZ_THREAD_COMMAND_BF_STATE 16
#define SZ_NLIST 12
/* the page size for x86 and PowerPC */ /* the page size for x86 and PowerPC */
#define CV_PGSZ 4096 #define CV_PGSZ 4096
@ -76,9 +81,33 @@ enum {
#define pg_mod(u) ((u) & (CV_PGSZ - 1)) #define pg_mod(u) ((u) & (CV_PGSZ - 1))
/* u rounded down to whole pages */ /* u rounded down to whole pages */
#define pg_trunc(u) ((u) & ~(CV_PGSZ - 1)) #define pg_trunc(u) ((u) & ~(CV_PGSZ - 1))
/* u rounded up to whole pages */
#define pg_round(u) pg_trunc((u) + (CV_PGSZ - 1))
const char zero_pg[CV_PGSZ] = { 0 };
/*
* machseg[0]: __PAGEZERO with address 0, size CV_PGSZ
* machseg[1]: __TEXT for ack TEXT, ROM
* machseg[2]: __DATA for ack DATA, BSS
*/
struct {
const char *ms_name;
uint32_t ms_vmaddr;
uint32_t ms_vmsize;
uint32_t ms_fileoff;
uint32_t ms_filesize;
uint32_t ms_prot;
uint32_t ms_nsects;
} machseg[3] = {
"__PAGEZERO", 0, CV_PGSZ, 0, 0, VM_PROT_NONE, 0,
"__TEXT", 0, 0, 0, 0, VM_PROT_READ | VM_PROT_EXECUTE, 2,
"__DATA", 0, 0, 0, 0, VM_PROT_READ | VM_PROT_WRITE, 2,
};
void usage(void) static void
usage(void)
{ {
fprintf(stderr, "Usage: %s -m<num> <inputfile> <outputfile>\n", fprintf(stderr, "Usage: %s -m<num> <inputfile> <outputfile>\n",
program); program);
@ -86,7 +115,8 @@ void usage(void)
} }
/* Produce an error message and exit. */ /* Produce an error message and exit. */
void fatal(const char* s, ...) static void
fatal(const char* s, ...)
{ {
va_list ap; va_list ap;
@ -103,22 +133,54 @@ void fatal(const char* s, ...)
exit(1); exit(1);
} }
void rd_fatal(void) void
rd_fatal(void)
{ {
fatal("read error"); fatal("read error");
} }
/* Calculate the result of a aligned to b (rounding up if necessary). /* Returns n such that 2**n == a. */
* b must be a power of two. */ static uint32_t
uint32_t align(uint32_t a, uint32_t b) log2u(uint32_t a)
{ {
a += b - 1; uint32_t n = 0;
return a & ~(b-1); while (a) {
a >>= 1;
n++;
}
return n - 1;
} }
/* Writes a byte. */
static void
emit8(uint8_t value)
{
writef(&value, 1, 1);
}
/* Writes out a 16-bit value in the appropriate endianness. */
static void
emit16(uint16_t value)
{
unsigned char buffer[2];
if (bigendian)
{
buffer[0] = (value >> 8) & 0xFF;
buffer[1] = (value >> 0) & 0xFF;
}
else
{
buffer[1] = (value >> 8) & 0xFF;
buffer[0] = (value >> 0) & 0xFF;
}
writef(buffer, 1, sizeof(buffer));
}
/* Writes out a 32-bit value in the appropriate endianness. */ /* Writes out a 32-bit value in the appropriate endianness. */
void emit32(uint32_t value) static void
emit32(uint32_t value)
{ {
unsigned char buffer[4]; unsigned char buffer[4];
@ -142,7 +204,8 @@ void emit32(uint32_t value)
/* Copies the contents of a section from the input stream /* Copies the contents of a section from the input stream
* to the output stream. */ * to the output stream. */
void emit_section(int section_nr) static void
emit_section(int section_nr)
{ {
struct outsect *section = &outsect[section_nr]; struct outsect *section = &outsect[section_nr];
size_t blocksize; size_t blocksize;
@ -160,50 +223,114 @@ void emit_section(int section_nr)
/* Zero fill any remaining space. */ /* Zero fill any remaining space. */
n = section->os_size - section->os_flen; n = section->os_size - section->os_flen;
if (n > 0) while (n > 0)
{ {
memset(buffer, 0, BUFSIZ); blocksize = (n > sizeof(zero_pg)) ? sizeof(zero_pg) : n;
while (n > 0) writef(zero_pg, 1, blocksize);
{ n -= blocksize;
blocksize = (n > BUFSIZ) ? BUFSIZ : n;
writef(buffer, 1, blocksize);
n -= blocksize;
}
} }
} }
void emit_lc_segment(char *name, uint32_t vm_ad, uint32_t vm_sz, static void
uint32_t f_off, uint32_t f_sz, int prot) emit_lc_segment(int i)
{ {
char namebuf[16]; uint32_t sz;
int flags, maxprot; int flags, maxprot;
char namebuf[16];
if (prot == VM_PROT_NONE) { if (i == 0) {
/* special values for __PAGEZERO */ /* special values for __PAGEZERO */
maxprot = VM_PROT_NONE; maxprot = VM_PROT_NONE;
flags = 4; /* NORELOC */ flags = 4; /* SG_NORELOC */
} else { } else {
maxprot = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE; maxprot = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE;
flags = 0; flags = 0;
} }
/*
* The size of this command includes the size of its section
* headers, see emit_section_header().
*/
sz = SZ_SEGMENT_COMMAND + machseg[i].ms_nsects * SZ_SECTION_HEADER;
/* Use strncpy() to pad namebuf with '\0' bytes. */ /* Use strncpy() to pad namebuf with '\0' bytes. */
strncpy(namebuf, name, sizeof(namebuf)); strncpy(namebuf, machseg[i].ms_name, sizeof(namebuf));
emit32(LC_SEGMENT); /* command */ emit32(LC_SEGMENT); /* command */
emit32(SZ_SEGMENT_COMMAND); /* size of command */ emit32(sz); /* size of command */
writef(namebuf, 1, sizeof(namebuf)); writef(namebuf, 1, sizeof(namebuf));
emit32(vm_ad); /* vm address */ emit32(machseg[i].ms_vmaddr); /* vm address */
emit32(vm_sz); /* vm size */ emit32(machseg[i].ms_vmsize); /* vm size */
emit32(f_off); /* file offset */ emit32(machseg[i].ms_fileoff); /* file offset */
emit32(f_sz); /* file size */ emit32(machseg[i].ms_filesize); /* file size */
emit32(maxprot); /* max protection */ emit32(maxprot); /* max protection */
emit32(prot); /* initial protection */ emit32(machseg[i].ms_prot); /* initial protection */
emit32(0); /* number of Mach sections */ emit32(machseg[i].ms_nsects); /* number of Mach sections */
emit32(flags); /* flags */ emit32(flags); /* flags */
} }
void emit_lc_unixthread(void) static void
emit_section_header(int ms, const char *name, int os)
{
uint32_t fileoff, flags;
char namebuf[16];
switch (os) {
case TEXT:
/* S_ATTR_PURE_INSTRUCTIONS | S_ATTR_SOME_INSTRUCTIONS */
flags = 0x80000400;
break;
case BSS:
flags = 0x1; /* S_ZEROFILL */
break;
default:
flags = 0x0; /* S_REGULAR */
break;
}
if (os == BSS)
fileoff = 0;
else
fileoff = machseg[ms].ms_fileoff +
(outsect[os].os_base - machseg[ms].ms_vmaddr);
/* name of Mach section */
strncpy(namebuf, name, sizeof(namebuf));
writef(namebuf, 1, sizeof(namebuf));
/* name of Mach segment */
strncpy(namebuf, machseg[ms].ms_name, sizeof(namebuf));
writef(namebuf, 1, sizeof(namebuf));
emit32(outsect[os].os_base); /* vm address */
emit32(outsect[os].os_size); /* vm size */
emit32(fileoff); /* file offset */
emit32(log2u(outsect[os].os_lign)); /* alignment */
emit32(0); /* offset of relocations */
emit32(0); /* number of relocations */
emit32(flags); /* flags */
emit32(0); /* reserved */
emit32(0); /* reserved */
}
static void
emit_lc_symtab(void)
{
uint32_t off1, off2;
/* Symbol table will be at next page after machseg[2]. */
off1 = pg_round(machseg[2].ms_fileoff + machseg[2].ms_filesize);
/* String table will be after symbol table. */
off2 = off1 + 12 * outhead.oh_nname;
emit32(LC_SYMTAB); /* command */
emit32(SZ_SYMTAB_COMMAND); /* size of command */
emit32(off1); /* offset of symbol table */
emit32(outhead.oh_nname); /* number of symbols */
emit32(off2); /* offset of string table */
emit32(1 + outhead.oh_nchar); /* size of string table */
}
static void
emit_lc_unixthread(void)
{ {
int i, ireg, ts, ts_count; int i, ireg, ts, ts_count;
@ -238,10 +365,111 @@ void emit_lc_unixthread(void)
} }
} }
static void
int main(int argc, char *argv[]) emit_symbol(struct outname *np)
{ {
uint32_t len2, len3, mach_base, pad, sz_bf_entry, sz_load_cmds; uint32_t soff;
uint8_t type;
uint8_t sect;
uint16_t desc;
if (np->on_type & S_STB) {
/* stab for debugger */
type = np->on_type >> 8;
desc = np->on_desc;
} else {
desc = 0;
switch (np->on_type & S_TYP) {
case S_UND:
type = 0x0; /* N_UNDF */
break;
case S_ABS:
type = 0x2; /* N_ABS */
break;
default:
type = 0xe; /* N_SECT */
break;
}
if (np->on_type & S_EXT)
type |= 0x1; /* N_EXT */
}
switch (np->on_type & S_TYP) {
case S_MIN + TEXT:
sect = 1;
break;
case S_MIN + ROM:
sect = 2;
break;
case S_MIN + DATA:
sect = 3;
break;
case S_MIN + BSS:
case S_MIN + NUM_SEGMENTS:
sect = 4;
break;
default:
sect = 0; /* NO_SECT */
break;
}
/*
* To find the symbol's name, ack.out uses an offset from the
* beginning of the file, but Mach-o uses an offset into the
* string table. Both formats use offset 0 for a symbol with
* no name. We will prepend a '\0' at offset 0, so every
* named symbol needs + 1.
*/
if (np->on_foff)
soff = np->on_foff - ack_off_char + 1;
else
soff = 0;
emit32(soff);
emit8(type);
emit8(sect);
emit16(desc);
emit32(np->on_valu);
}
static void
emit_symtab(void)
{
struct outname *names, *np;
int i;
char *chars;
/* Using calloc(a, b) to check if a * b would overflow. */
names = calloc(outhead.oh_nname, sizeof(struct outname));
if (!names)
fatal("out of memory");
chars = malloc(outhead.oh_nchar);
if (!names || !chars)
fatal("out of memory");
rd_name(names, outhead.oh_nname);
rd_string(chars, outhead.oh_nchar);
ack_off_char = OFF_CHAR(outhead);
/* Emit each symbol entry. */
for (i = 0, np = names; i < outhead.oh_nname; i++, np++)
emit_symbol(np);
/*
* Emit the string table. The first character of a Mach-o
* string table must be '\0', so we prepend a '\0'.
*/
emit8(0);
writef(chars, 1, outhead.oh_nchar);
}
int
main(int argc, char *argv[])
{
uint32_t end, pad[3], sz, sz_load_cmds;
int cpu_subtype, mflag = 0; int cpu_subtype, mflag = 0;
/* General housecleaning and setup. */ /* General housecleaning and setup. */
@ -323,54 +551,62 @@ int main(int argc, char *argv[])
rd_sect(outsect, outhead.oh_nsect); rd_sect(outsect, outhead.oh_nsect);
/* /*
* 1st Mach segment: __PAGEZERO * machseg[1] will start at a page boundary and include the
* 2nd Mach segment: __TEXT * Mach header and load commands before ack TEXT and ROM.
* Mach headers and load commands *
* ack TEXT * Find our entry point (immediately after the load commands)
* ack ROM * and check that TEXT begins there.
* 3rd Mach segment: __DATA
* ack DATA
* ack BSS
*/ */
machseg[1].ms_vmaddr = pg_trunc(outsect[TEXT].os_base);
/* Find entry point and check that TEXT begins there. */ sz_load_cmds = 3 * SZ_SEGMENT_COMMAND + 4 * SZ_SECTION_HEADER +
mach_base = pg_trunc(outsect[TEXT].os_base); SZ_SYMTAB_COMMAND + sz_thread_command;
sz_load_cmds = 3 * SZ_SEGMENT_COMMAND + sz_thread_command; entry = machseg[1].ms_vmaddr + SZ_MACH_HEADER + sz_load_cmds;
sz_bf_entry = SZ_MACH_HEADER + sz_load_cmds;
entry = mach_base + sz_bf_entry;
if (entry != outsect[TEXT].os_base) { if (entry != outsect[TEXT].os_base) {
fatal("text segment must have base 0x%lx, not 0x%lx\n", fatal("text segment must have base 0x%lx, not 0x%lx"
entry, outsect[TEXT].os_base); "\n\t(suggest em_led -b0:0x%lx)",
(unsigned long)entry,
(unsigned long)outsect[TEXT].os_base,
(unsigned long)entry);
} }
/* Check that ROM can follow TEXT in 2nd Mach segment. */ /* Pad for alignment between TEXT and ROM. */
outsect[TEXT].os_size = sz = outsect[ROM].os_base - outsect[TEXT].os_base;
align(outsect[TEXT].os_size, outsect[ROM].os_lign); pad[0] = sz - outsect[TEXT].os_size;
if (outsect[ROM].os_base != if (sz < outsect[TEXT].os_size || pad[0] >= outsect[ROM].os_lign)
outsect[TEXT].os_base + outsect[TEXT].os_size)
fatal("the rom segment must follow the text segment."); fatal("the rom segment must follow the text segment.");
/* /*
* Insert padding between ROM and DATA, such that * Pad between ROM and DATA such that we can map machseg[2] at
* pg_mod(len2) == pg_mod(outsect[DATA].os_base) * a page boundary with DATA at its correct base address.
* *
* This will allow us to map the 3rd Mach segment at the * For example, if ROM ends at 0x2bed and DATA begins at
* beginning of a page, such that DATA is at its base. * 0x3000, then we pad to the page boundary. If ROM ends at
* 0x2bed and DATA begins at 0x3bf0, then pad = 3 and we map
* the page twice, at both 0x2000 and 0x3000.
*/ */
len2 = sz_bf_entry + outsect[TEXT].os_size + outsect[ROM].os_size; end = outsect[ROM].os_base + outsect[ROM].os_size;
pad = pg_mod(outsect[DATA].os_base - len2); pad[1] = pg_mod(outsect[DATA].os_base - end);
outsect[ROM].os_size += pad;
len2 = pg_trunc(len2 + pad); sz = end - machseg[1].ms_vmaddr;
machseg[1].ms_vmsize = machseg[1].ms_filesize = sz;
machseg[2].ms_vmaddr = pg_trunc(outsect[DATA].os_base);
machseg[2].ms_fileoff = pg_trunc(sz + pad[1]);
if (machseg[2].ms_vmaddr < end &&
machseg[2].ms_vmaddr >= machseg[1].ms_vmaddr)
fatal("the data and rom segments are too close."
"\n\t(suggest em_led -a2:%d)", (int)CV_PGSZ);
/* Check that BSS can follow DATA in 3rd Mach segment. */
if (outsect[BSS].os_flen != 0) if (outsect[BSS].os_flen != 0)
fatal("the bss space contains initialized data."); fatal("the bss space contains initialized data.");
if (outsect[BSS].os_base < sz = outsect[BSS].os_base - outsect[DATA].os_base;
outsect[DATA].os_base + outsect[DATA].os_size) if (sz < outsect[DATA].os_size ||
sz - outsect[DATA].os_size >= outsect[BSS].os_lign)
fatal("the bss segment must follow the data segment."); fatal("the bss segment must follow the data segment.");
len3 = outsect[BSS].os_base - pg_trunc(outsect[DATA].os_base) + end = outsect[DATA].os_base + outsect[DATA].os_size;
outsect[BSS].os_size; machseg[2].ms_filesize = end - machseg[2].ms_vmaddr;
end = outsect[BSS].os_base + outsect[BSS].os_size;
machseg[2].ms_vmsize = end - machseg[2].ms_vmaddr;
if (outhead.oh_nsect == NUM_SEGMENTS + 1) { if (outhead.oh_nsect == NUM_SEGMENTS + 1) {
if (outsect[NUM_SEGMENTS].os_base != if (outsect[NUM_SEGMENTS].os_base !=
@ -380,37 +616,43 @@ int main(int argc, char *argv[])
fatal("end segment must be empty"); fatal("end segment must be empty");
} }
/*
* Pad to page boundary between BSS and symbol table.
*
* Also, some versions of Mac OS X refuse to load any
* executable smaller than 4096 bytes (1 page).
*/
pad[2] = pg_mod(-(uint32_t)machseg[2].ms_filesize);
/* Emit the Mach header. */ /* Emit the Mach header. */
emit32(MH_MAGIC); /* magic */ emit32(MH_MAGIC); /* magic */
emit32(cpu_type); /* cpu type */ emit32(cpu_type); /* cpu type */
emit32(cpu_subtype); /* cpu subtype */ emit32(cpu_subtype); /* cpu subtype */
emit32(MH_EXECUTE); /* file type */ emit32(MH_EXECUTE); /* file type */
emit32(4); /* number of load commands */ emit32(5); /* number of load commands */
emit32(sz_load_cmds); /* size of load commands */ emit32(sz_load_cmds); /* size of load commands */
emit32(0); /* flags */ emit32(0); /* flags */
/* vm address: vm size: emit_lc_segment(0);
* 1st Mach segment: NULL CV_PGSZ emit_lc_segment(1);
* 2nd Mach segment: mach_base len2 emit_section_header(1, "__text", TEXT);
* 3rd Mach segment: mach_base+len2 len3 emit_section_header(1, "__rom", ROM);
* emit_lc_segment(2);
* file offset: file size: emit_section_header(2, "__data", DATA);
* 2nd Mach segment: 0 len2 emit_section_header(2, "__bss", BSS);
* 3rd Mach segment: len2 DATA os_size emit_lc_symtab();
*/
emit_lc_segment("__PAGEZERO", 0 /* NULL */, CV_PGSZ,
0, 0, VM_PROT_NONE);
emit_lc_segment("__TEXT", mach_base, len2,
0, len2, VM_PROT_READ | VM_PROT_EXECUTE);
emit_lc_segment("__DATA", mach_base + len2, len3,
len2, outsect[DATA].os_size, VM_PROT_READ | VM_PROT_WRITE);
emit_lc_unixthread(); emit_lc_unixthread();
/* Emit non-empty sections. */ /* Emit non-empty sections. */
emit_section(TEXT); emit_section(TEXT);
writef(zero_pg, 1, pad[0]);
emit_section(ROM); emit_section(ROM);
writef(zero_pg, 1, pad[1]);
emit_section(DATA); emit_section(DATA);
writef(zero_pg, 1, pad[2]);
emit_symtab();
if (ferror(output)) if (ferror(output))
fatal("write error"); fatal("write error");

2
plat/osx386/descr
View file

@ -18,7 +18,7 @@ var ARCH=i386
var PLATFORM=osx386 var PLATFORM=osx386
var PLATFORMDIR={EM}/share/ack/{PLATFORM} var PLATFORMDIR={EM}/share/ack/{PLATFORM}
var CPP_F=-D__unix var CPP_F=-D__unix
var ALIGN=-a0:4 -a1:4 -a2:4096 -a3:4 -b0:0x1114 var ALIGN=-a0:4 -a1:4 -a2:4096 -a3:4 -b0:0x123c
var C_LIB={PLATFORMDIR}/libc-ansi.a var C_LIB={PLATFORMDIR}/libc-ansi.a
# bitfields reversed for compatibility with (g)cc. # bitfields reversed for compatibility with (g)cc.
var CC_ALIGN=-Vr var CC_ALIGN=-Vr

2
plat/osxppc/descr
View file

@ -18,7 +18,7 @@ var ARCH=powerpc
var PLATFORM=osxppc var PLATFORM=osxppc
var PLATFORMDIR={EM}/share/ack/{PLATFORM} var PLATFORMDIR={EM}/share/ack/{PLATFORM}
var CPP_F=-D__unix var CPP_F=-D__unix
var ALIGN=-a0:4 -a1:4 -a2:4096 -a3:4 -b0:0x1174 var ALIGN=-a0:4 -a1:4 -a2:4096 -a3:4 -b0:0x129c
var C_LIB={PLATFORMDIR}/libc-ansi.a var C_LIB={PLATFORMDIR}/libc-ansi.a
# bitfields reversed for compatibility with (g)cc. # bitfields reversed for compatibility with (g)cc.
# XXX this is from linux386, might be wrong for osxppc # XXX this is from linux386, might be wrong for osxppc